Molds and methods of forming molds associated with manufacture of rotary drill bits and other downhole tools

ABSTRACT

Three dimensional printing equipment and techniques may be used in combination with three dimensional design data associated with well drilling equipment and well completion equipment to form molds associated with manufacture of such equipment. For example, such molds may be used to form a bit body or other components associated with a rotary drill bit. For some applications composite or matrix materials may be placed in the mold to form a matrix bit body. Heat transfer characteristics of the mold may be optimized for heating and/or cooling of the matrix materials to provide optimum fracture resistant (toughness) and optimum erosion, abrasion and/or wear resistance for portions of the bit body. Such molds may also be used to form steel bit bodies associated with fixed cutter rotary drill bits and other components associated with a wide variety of well drilling equipment and well completion equipment.

RELATED APPLICATION

This application claims the benefit of U.S. Provisional PatentApplication entitled “ROTARY DRILL BITS AND METHODS OF FORMING MOLDSASSOCIATED WITH MANUFACTURE OF ROTARY DRILL BIT”, application Ser. No.60/745,975 filed Apr. 28, 2006.

TECHNICAL FIELD

The present disclosure is related to molds, methods of forming molds andmore particularly to fixed cutter drill bits and other downhole toolsassociated with forming and/or completing wellbores.

BACKGROUND OF THE DISCLOSURE

Rotary drill bits are frequently used to drill oil and gas wells,geothermal wells and water wells. Rotary drill bits may be generallyclassified as rotary cone or roller cone drill bits and fixed cutterdrilling equipment or drag bits. Fixed cutter drill bits or drag bitsare often formed with a bit body having cutting elements or insertsdisposed at select locations of exterior portions of the bit body. Fluidflow passageways are typically formed in the bit body to allowcommunication of drilling fluids from associated surface drillingequipment through a drill string or drill pipe attached to the bit body.

Fixed cutter drill bits generally include a metal shank operable forengagement with a drill string or drill pipe. Various types of steelalloys may be used to form a metal shank. A bit head may be attached toan associated shank to form a resulting bit body.

For some applications a bit head may be formed from various types ofsteel alloys satisfactory for use in drilling a wellbore through adownhole formation. The resulting bit body may sometimes be described asa “steel bit body.” For other applications, a bit head may be formed bymolding hard, refractory materials with a metal blank. A steel shank maybe attached to the metal blank. The resulting bit body may be describedas a “matrix bit body.” Fixed cutter drill bits or drag bits formed withmatrix bit bodies may sometimes be referred to as “matrix drill bits.”

Matrix drill bits are often formed by placing loose infiltrationmaterial or matrix material (sometimes referred to as “matrix powder”)into a mold and infiltrating the matrix material with a binder such as acopper alloy. Other metallic alloys may also be used as a binder.Infiltration materials may include various refractory materials. Apreformed metal blank or bit blank may also be placed in the mold toprovide reinforcement for a resulting matrix bit head. The mold may beformed by milling a block of material such as graphite to define a moldcavity with features corresponding generally with desired exteriorfeatures of a resulting matrix drill bit.

Various features of a resulting matrix drill bit such as blades, cutterpockets, and/or fluid flow passageways may be provided by shaping themold cavity and/or by positioning temporary displacement material withininterior portions of the mold cavity. An associated metal shank may beattached to the bit blank after the matrix bit head has been removedfrom the mold. The metal shank may be used to attach of the resultingmatrix drill bit with a drill string.

A wide variety of molds has been used to form matrix bit bodies andassociated matrix drill bits. U.S. Pat. No. 5,373,907 entitled “MethodAnd Apparatus For Manufacturing And Inspecting The Quality Of A MatrixBody Drill Bit” shows some details concerning conventional moldassemblies and matrix bit bodies.

A wide variety of molds and castings produced by such molds have beenused to form steel bit bodies and associated fixed cutter drill bits.

SUMMARY OF THE DISCLOSURE

In accordance with teachings of the present disclosure, threedimensional (3D) printing equipment and techniques may be used incombination with three dimensional (3D) design data associated with awide variety of well drilling equipment and well completion equipment toform molds for producing various components associated with suchequipment. For some applications refractory materials, infiltrationmaterials and/or matrix materials, typically in a powder form, may beplaced in such molds. For other applications molten steel alloys orother molten metal alloys may be poured into such molds. Heat transfercharacteristics of such molds may be optimized for both heating andcooling of matrix materials or cooling of molten metal alloys to provideoptimum fracture resistant (toughness), optimum tensile strength and/oroptimum erosion, abrasion and/or wear resistance of resultingcomponents.

Combining characteristics of a 3D printer with 3D design data may allowgreater freedom to design molds having mold cavities with complexconfigurations and dimensions as compared to more limited design optionswhen using conventional mold forming techniques. Manufacturing costs forsuch molds and associated components may also be reduced as comparedwith some conventional mold forming techniques.

One aspect of the present disclosure may include using three dimensional(3D) printing equipment and techniques in combination with threedimensional (3D) computer aided design (CAD) data associated with fixedcutter drill bits to produce respective molds having a “negative image”of various portions of each fixed cutter drill bit. Such molds may beused to form a matrix bit head or a steel bit head for a respectivefixed cutter drill bit.

Another aspect of the present disclosure may include using 3D printingequipment and techniques in combination with 3D CAD data associated withcore bits, open hole reamers, near bit reamers and other downhole toolsto produce respective molds having a “negative image” of variouscomponents of such well tools.

Teachings of the present disclosure may include using 3D printingequipment and techniques in combination with 3D CAD data associated withcore bits, open hole reamers, near bit reamers and other downhole toolsto produce respective molds having a “negative image” of variouscomponents of such well tools.

A further aspect of the present disclosure may include using 3D printingequipment and techniques in combination with 3D design data to directlyproduce various components associated with fixed cutter drill bits andother types of downhole tools without the use of molds. Such downholetools may be used to form wellbores in downhole formations (welldrilling equipment or well drilling tools) or may be used to complete awellbore extending through a downhole formation (well completionequipment or well completion tools).

Another aspect of the present disclosure may include using 3D printingequipment in combination with 3D design data to form respective portionsof a mold from materials having different thermal conductivity and/orelectrical conductivity characteristics. For example, providing highthermal conductivity proximate a first end or bottom portion of a moldmay improve heat transfer during heating and cooling of materialsdisposed within the mold. Thermal conductivity may be relatively lowproximate a second end or top portion of the mold to function as aninsulator for better control of heating and/or cooling of materialsdisposed within the mold.

A mold formed in accordance with teachings of the present disclosure mayhave variations in electrical conductivity to accommodate varyingheating and/or cooling rates of materials disposed within the mold. Forexample, one or more portions of the mold may be formed from materialshaving electrical conductivity characteristics compatible with anassociated microwave heating system or an induction heating system. As aresult, such portions of the mold may be heated to a higher temperatureand/or heated at a higher rate than other portions of the mold which donot have such electrical conductivity characteristics.

Another aspect of the present disclosure may include placing degassingchannels at optimum locations within a mold to allow degassing or offgassing of materials disposed within the mold. Fluid flow channels maybe placed at optimum locations on interior and/or exterior portions of amold with optimum configurations to heat and/or cool materials disposedwithin the mold. Various types of liquids and/or gases may be circulatedthrough such fluid flow channels.

Prior art references have previously discussed potential benefits offorming a mold having fluid flow channels to optimize heating, coolingand/or degassing of materials during solidication within the mold.However, previously available machining techniques and conventional moldforming techniques have limited the ability to effectively commercializeuse of such heating, cooling and/or degassing fluid channels.

For some embodiments, interior portions of a mold or mold cavity may becoated by a mold wash to prevent gases produced by heating the mold fromentering into powders or matrix materials disposed within the moldcavity. The mold wash may form a diffusion barrier or create a skineffect to prevent off gases from mold materials migrating into matrixmaterials or other materials disposed within the mold cavity.

BRIEF DESCRIPTION OF THE DRAWINGS

A more complete and thorough understanding of the present embodimentsand advantages thereof may be acquired by referring to the followingdescription taken in conjunction with the accompanying drawings, inwhich like reference numbers indicate like features, and wherein:

FIG. 1 is a schematic drawing in section with portions broken awayshowing one example of a prior art mold which may be used to form a bithead for a matrix bit body;

FIG. 2 is a schematic drawing showing an interior view of a mold such asshown in FIG. 1;

FIG. 3 is a schematic drawing in section with portions broken awayshowing one example of a fixed cutter bit body formed by a mold such asshown in FIGS. 1 and 2;

FIG. 4 is a schematic drawing showing an isometric view of one exampleof a fixed cutter drill bit having a matrix bit body which may be formedin accordance with teachings of the present disclosure;

FIG. 5A is a schematic drawing showing a isometric view of a mold formedin accordance with teachings of the present disclosure which may be usedto form a bit head for a fixed cutter rotary drill bit;

FIG. 5B is a schematic drawing showing another isometric view of themold of FIG. 5A;

FIG. 5C is a drawing in section taken along lines 5C-5C of FIG. 5B;

FIG. 5D is a schematic drawing in section taken along lines 5D-5D ofFIG. 5C;

FIG. 6 is a schematic drawing in section showing a mold formed inaccordance with teachings of the present disclosure disposed within acontainer satisfactory for heating the mold and matrix materialsdisposed within the mold;

FIG. 7 is a schematic drawing showing a roller cone drill bit which mayinclude various components formed in accordance with teachings of thepresent disclosure; and

FIG. 8 is a schematic drawing in elevation showing one example of asupport arm for a roller cone drill bit which may be formed inaccordance with teachings of the present disclosure.

DETAILED DESCRIPTION OF THE DISCLOSURE

Preferred embodiments of the disclosure and its advantages are bestunderstood by reference to FIGS. 1-8 wherein like number refer to sameand like parts.

Various features and steps of the present disclosure may be describedwith respect to forming a bit body for a rotary drill bit. Portions ofthe bit body formed in a mold may be referred to as a “bit head.” Forsome embodiments a “bit body” may generally be described as a bit headwith a metal shank attached thereto. Some prior art references may referto a bit head (as used in this application) as a bit body. Some bitbodies may be formed with an integral bit head and metal shank inaccordance with teachings of the present disclosure.

For purposes of describing various features and steps of the presentdisclosure, the terms “downhole tool” and “downhole tools” may be usedto describe well drilling equipment, well drilling tools, wellcompletion equipment, well completion tools and/or associated componentswhich may be manufactured using molds formed in accordance withteachings of the present disclosure. Examples of such well completiontools and/or associated components (not expressly shown) which may beformed at least in part by molds incorporating teachings of the presentdisclosure may include, but are not limited to, whipstocks, productionpacker components, float equipment, casing shoes, casing shoes withcutting structures, well screen bodies and connectors, gas liftmandrels, downhole tractors for pulling coiled tubing, tool joints,wired (electrical and/or fiber optic) tool joints, drill in wellscreens, rotors, stator and/or housings for downhole motors, bladesand/or housings for downhole turbines, latches for downhole tools,downhole wireline service tools and other downhole tools have complexconfigurations and/or asymmetric geometries associated with competing awellbore. Molds incorporating teachings of the present disclosure may beused to form elastomeric and/or rubber components for such wellcompletion tools. Various well completion tools and/or components mayalso be formed using a 3D printer in combination with 3D design data inaccordance with teaching of the present disclosure.

Examples of well drilling tools and associated components (not expresslyshown) which may be formed at least in part by molds incorporatingteachings of the present disclosure may include, but are not limited to,non-retrievable drilling components, aluminum drill bit bodiesassociated with casing drilling of wellbores, drill string stabilizers,cones for roller cone drill bits, models for forging dyes used tofabricate support arms for roller cone drill bits, arms for fixedreamers, arms for expandable reamers, internal components associatedwith expandable reamers, sleeves attached to an up hole end of a rotarydrill bit, rotary steering tools, logging while drilling tools,measurement while drilling tools, side wall coring tools, fishingspears, washover tools, rotors, stators and/or housing for downholedrilling motors, blades and housings for downhole turbines, and otherdownhole tools having complex configurations and/or asymmetricgeometries associated with forming a wellbore. Molds incorporatingteachings of the present disclosure may be used to form a elastomericand/or rubber components for such well drilling tools. Various welldrilling tools and/or components may also be formed using a 3D printerin combination with 3D design data in accordance with teachings of thepresent disclosure.

For purposes of describing various features and steps of the presentdisclosure, the terms “downhole tool” and “downhole tools” may also beused to describe well drilling equipment, well drilling tools, wellcompletion equipment, well completion tools and/or associated componentswhich may be directly formed using 3D printing equipment and techniquesin combination with 3D design data in accordance with teachings of thepresent disclosure.

Various techniques have previously been used to form molds associatedwith fabrication of matrix bit bodies and/or steel bit bodies for fixedcutter drill bits. For example numerically controlled machines and/ormanual machining processes have been used to fabricate molds fromvarious types raw material blanks. For example, graphite based materialsin the form of solid, cylindrical blanks have been machined to form amold cavity with dimensions and configurations that represent a negativeimage of a bit head for an associated matrix drill bit.

Mold assembly 100 as shown in FIGS. 1 and 2 represents only one exampleof a wide variety of molds which have previously been used to formmatrix bit heads and associated matrix drill bits. U.S. Pat. No.5,373,907 entitled Method And Apparatus For Manufacturing And InspectingThe Quality Of A Matrix Body Drill Bit shows additional detailsconcerning conventional mold assemblies and matrix bit bodies.

Mold assembly 100 as shown in FIGS. 1 and 2 may include severalcomponents such as mold 102, gauge ring or connector ring 110 and funnel120. Mold 102, gauge ring 110 and funnel 120 may be formed from graphiteor other suitable materials. Various techniques may be used including,but not limited to, machining a graphite blank to produce mold 102 withcavity 104 having a negative profile or a reverse profile of desiredexterior features for a resulting fixed cutter drill bit. See FIG. 2.For example cavity 104 may have a negative profile which correspondswith an exterior profile or configuration for blades 52 and junk slotsor fluid flow passageways 50 formed therebetween for a matrix drill bit.One example of a matrix drill bit is shown in FIG. 4.

As shown in FIGS. 1 and 2, a plurality of mold inserts 106 may be placedwithin cavity 104 to form respective pockets 62 in blades 54. Pockets 60may also be described as “sockets” or “receptacles.” Mold inserts 106may be disposed in cavity 104 at locations generally corresponding withdesired locations for installing cutting elements 64 in associatedblades 54. Mold inserts 106 may be formed from various types of materialsuch as, but not limited to, consolidated sand and graphite. Varioustechniques such as brazing may be satisfactorily used to install cuttingelements 62 in respective pockets 60 after bit head 52 has been removedfrom mold assembly 100.

Various types of displacement materials, mold inserts and/or preformsmay be temporarily or permanently disposed within mold cavity 104,depending upon each desired configuration for a resulting matrix drillbit. Such mold inserts, displacements and/or preforms (not expresslyshown) may be formed from various materials including, but not limitedto, consolidated sand and/or graphite. Various resins may besatisfactorily used to form consolidated sand. Such mold inserts,displacements and/or preforms may have configurations corresponding withdesired exterior features of a matrix bit body including, but notlimited to, fluid flow passageways or junk slots formed between adjacentblades.

As discussed later in more detail, teachings of the present disclosureallow forming molds with interior and/or exterior configurations anddimensions which may not be commercially possible to form usingconventional machining and/or other mold forming techniques. Teachingsof the present disclosure may also allow forming molds with optimumvariations in thermal conductivity and/or electrical conductivity.

Matrix bit body 50 as shown in FIG. 3 may include matrix bit head 52 andmetal shank 30 (shown in dotted lines). A relatively large fluid cavityor chamber with multiple fluid flow passageways 42 and 44 extendingtherefrom may be formed within matrix bit head 52. As shown in FIG. 1,displacement materials such as consolidated sand core 150 may beinstalled within mold assembly 100 at desired locations to form portionsof a large fluid cavity with fluid flow passages 42 and 44 extendingtherefrom. Fluid flow passageways 42 and 44 may be operable to receivethreaded receptacles (not expressly shown) for holding respectivenozzles 60 therein. See FIG. 4.

Relatively large, generally cylindrically shaped consolidated sand core150 may be placed on legs 142 and 144 formed from consolidated sand.Core 150 may also be referred to as a “stalk.” Core 150 and legs 142 and144 may be sometimes described as having the shape of a “crow's foot.”The number of legs 142 and 144 extending from core 150 may depend uponthe desired number of nozzle openings in a resulting matrix bit head.Legs 142 and 144 and core 150 may also be formed from graphite or othersuitable materials. Teachings of the present disclosure allow formingfluid flow passageways and nozzle receptacles with optimumconfigurations, dimensions and/or orientations within an associated bithead that may not be possible using consolidated sand and/or otherconventional mold forming techniques.

After desired displacement materials, including core 150 and legs 142and 144, have been installed within mold assembly 100, at least onematrix material, typically in powder form, may be placed therein. Forprior art examples represented by FIGS. 1 and 3, first matrix material131 having optimum fracture resistance characteristics (toughness) andoptimum erosion, abrasion and wear resistance, may be placed within moldassembly 100. First matrix material 131 may form a first zone or a firstlayer which will correspond approximately with exterior portions ofcomposite matrix bit body 50 which contact and remove formationmaterials during drilling of a wellbore. The amount of first matrixmaterial 131 add to mold assembly 120 will preferably be limited suchthat matrix material 131 does not contact end 152 of sand core 150.

A generally hollow, cylindrical metal blank 36 may also be placed withinmold assembly 100. Metal blank 36 may include inside diameter 37 whichis larger than the outside diameter of sand core 150. Various fixtures(not expressly shown) may be used to position metal blank 36 within moldassembly 100 at a desired location spaced from first matrix material131.

Second matrix material 132 may then be loaded into mold assembly 100 tofill a void space or annulus formed between outside diameter 154 of sandcore 150 and inside diameter 37 of metal blank 36. Second matrixmaterial 132 may cover first matrix material 131 including portions offirst matrix material 131 located adjacent to and spaced from end 152 ofcore 150. Second matrix material 132 may be primarily used to forminterior portions of matrix bit body 50 and exterior portions of matrixbit body 50 which typically do not contact adjacent downhole formationmaterials while forming a wellbore.

For some applications third matrix material 133 may be placed withinmold assembly 100 between outside diameter 40 of metal blank 36 andinside diameter 122 of funnel 120. Third matrix material 133 may besubsequently machined to provide a desired exterior configuration andtransition between matrix bit head 52 and metal shank 36. See FIGS. 1and 3.

A wide variety of equipment and procedures have been developed to formmodels, molds and prototypes using automated layering devices. U.S. Pat.No. 6,353,771 entitled “Rapid Manufacturing Of Molds For Forming DrillBits” provides examples of such equipment and procedures.

Various techniques and procedures have also been developed to use threedimensional (3D) printers to form models, molds and prototypes using 3Ddesign data. See, for example, information available at the websites ofZ Corporation (www.zcorp.com) and Prometal, a division of The Ex OneCompany (www.prometal.com).

U.S. Pat. No. 5,204,055 entitled 3-Dimensional Printing Techniques andRelated Patents discusses various techniques such as ink jet printing todeposit thin layers of material and inject binder material to bond eachlayer of powder material. Such techniques have been used to “print”molds satisfactory for metal casting of relatively complexconfigurations. U.S. Pat. No. 7,070,734 entitled “Blended PowderSolid—Supersolidus Liquid Phase Sentencing” and U.S. Pat. No. 7,087,109entitled “Three Dimensional Printing Material System and Method” alsodisclose various features of 3D printing equipment which may be usedwith 3D design data.

Binder material including, but not limited to, metallic alloys of copper(Cu), nickel (Ni), magnesium (Mn), lead (Pb), tin (Sn), cobalt (Co) andsilver (Ag) may be used with some embodiments of the present disclosure.Phosphorous (P) may sometimes be added in small quantities to reduceliquidity temperature of infiltration materials disposed in a mold.Various mixtures of such metallic alloys may also be used.

For some applications three dimensional (3D) design data for a fixedcutter drill bit such as shown in FIG. 4 may be used in combination with3D printing equipment and techniques to form a mold having a mold cavitywith a “negative image” of exterior portions of the fixed cutter drillbit. See FIGS. 5A-5D and 6. Various types of mold cavity inserts,displacements, preforms and other mold related structures may also befabricated in accordance with teachings of the present disclosure using3D design data and a 3D printer in accordance with teachings of thepresent disclosure. The use of 3D printing equipment and techniques mayresult in a higher level of accuracy and reduced cost per mold or moldcavity insert. For some applications 3D printing equipment andtechniques may be capable of producing molds with complexconfigurations, dimensions and/or tolerances that may not be possible tocommercially produce at reasonable costs using conventional numericallycontrolled machines, manual machining techniques, consolidated sandpreforms and/or other conventional mold forming techniques.

The use of 3D printing equipment and techniques in combination with 3Ddesign data may eliminate the need for programming a numericallycontrolled machine and milling a mold from a graphite blank or othersuitable blank. The use of 3D printing equipment and techniques incombination with 3D design data may allow forming complex geometricalconfigurations associated with sockets or pockets for installing cuttingelements in exterior portions of a bit body as an integral part of amold cavity. Complex configurations for cutter blades, junk slots, armsassociated with under reamers (not expressly shown) and other componentsof various downhole tools may be formed as an integral part of a moldcavity. The number of mold cavity inserts and/or preforms required toform a bit head or other components of well drilling tools and wellcompletion tools may be substantially reduced or eliminated.

Using 3D printing equipment and techniques in combination with 3D designdata in accordance with teachings of the present disclosure mayeliminate many manufacturing problems associated with fabrication ofmolds used to form matrix bit heads and other components of rotary drillbits. Using 3D printing equipment and techniques in combination with 3Ddesign data in accordance with teachings of the present disclosure mayeliminate the need for using molds to form bit heads, bit bodies andother components associated with well drilling tools and/or wellcompletion tools.

FIG. 4 is a schematic drawing showing one example of a fixed cutterdrill bit or rotary drill bit having a bit head which may be formed in amold incorporating teachings of the present disclosure. Such bit headsmay sometimes be referred to as matrix bit heads or composite bit heads.At least one matrix material, often in powder form, may be placed in amold formed in accordance with teachings of the present disclosure.

Matrix materials may sometimes be referred to as refractory materials orinfiltration materials. Examples of such matrix materials may include,but are not limited to, tungsten carbide, monotungsten carbide (WC),ditungsten carbide (W₂C), macrocrystalline tungsten carbide, other metalcarbides, metal borides, metal oxides, metal nitrides andpolycrystalline diamond (PCD). Examples of other metal carbides mayinclude, but are not limited to, titanium carbide and tantalum carbide.Various mixtures of such materials may also be used.

A mold, filled with at least one matrix material and at least onebinder, may be heated and cooled to form a matrix bit head. For someapplications two or more different types of matrix materials or powdersmay be disposed in the mold. A resulting drill bit may sometimes bereferred to as a matrix drill bit.

For some embodiments drill bit 20 may include matrix bit head 52 formedin a mold incorporating teachings of the present disclosure. For otherapplications matrix bit head 52 may be directly formed from refractorymaterials using a 3D printer and associated techniques in combinationwith 3D design data in accordance with teachings of the presentdisclosure.

Metal shank 30 may be described as having a generally hollow,cylindrical configuration defined in part by a fluid flow passageway(not expressly shown). Various types of threaded connections, such asAmerican Petroleum Institute (API) connection or threaded pin 34, may beformed on metal shank 30. Shank 30 may be attached to metal blank 36after bit head 52 has been removed from an associated mold. Shank 30 andbit head 52 when attached to each other form resulting matrix bit body50. Cutting elements 64 may be disposed in respective pockets 62 afterbit body 50 has been formed to provide rotary drill bit 20.

Generally cylindrical metal shank 30 may be attached to hollow, metalblank 36 using various techniques. For example an annular weld groove 38may be formed between adjacent portions of shank 30 and hollow, metalblank 36. Weld 39 may be formed in annular weld groove 38 to securelyattach portions of shank 30 with adjacent portions of hollow metal blank36. A fluid flow passageway or longitudinal bore (not expressly shown)may extend through metal shank 30 and metal blank 36.

A plurality of nozzle openings 58 may formed in matrix bit body 50.Respective nozzles 60 may be disposed in each nozzle opening 58. Forsome applications nozzles 60 may be described as “interchangeable”nozzles. Various types of drilling fluid may be pumped from surfacedrilling equipment (not expressly shown) through a drill string (notexpressly shown) attached with threaded connection 34 and associatedfluid flow passageways (not expressly shown) to exit from one or morenozzles 60. The cuttings, downhole debris, formation fluids and/ordrilling fluid may return to the well surface through an annulus (notexpressly shown) formed between exterior portions of the drill stringand interior of an associated wellbore (not expressly shown).

For embodiments such as shown in FIG. 4, a plurality of cutter blades 54may be disposed on exterior portions of matrix bit body 50. Cutterblades 54 may be spaced from each other on the exterior of matrix bitbody 50 to form fluid flow paths or junk slots 56 therebetween.

A plurality of pockets or recesses 62 may be formed in blades 52 atselected locations. Respective cutting elements or inserts 64 may besecurely mounted in each pocket 62 to engage and remove adjacentportions of a downhole formation. Cutting elements 64 may scrape andgouge adjacent formation materials to form a wellbore during rotation ofdrill bit 20 by an attached drill string (not expressly shown). For someapplications various types of polycrystalline diamond compact (PDC)cutting elements may be satisfactorily used as inserts 60. Drill bitshaving such PDC cutters may sometimes be referred to as a “PDC bit”.

U.S. Pat. No. 6,296,069 entitled “Bladed Drill Bit with CentrallyDistributed Diamond Cutters” and U.S. Pat. No. 6,302,224 entitled“Drag-Bit Drilling with Multiaxial Tooth Inserts” show various examplesof blades and/or cutting elements which may be used with a matrix bitbody formed in accordance with teachings of the present disclosure. Itwill be readily apparent to persons having ordinary skill in the artthat a wide variety of fixed cutter drill bits, drag bits and othertypes of rotary drill bits may be satisfactorily formed from a bit bodymolded in accordance with teachings of the present disclosure. Thepresent disclosure is not limited to drill bit 20 or any specificfeatures discussed in the application.

A wide variety of powders and binders have previously been used with 3Dprinters to form various types of molds and other complex threedimensional products. For some applications 3D printing equipment may beused to deposit relatively thin layers of powder having dimensionscorresponding with associated 3D design data for a fixed cutter drillbit. 3D printing equipment may include a printer head operable to ejectone or more types of binder into each thin layer of powder.

For some applications powder layers may be formed from graphite basedmaterials, boron nitride based materials and/or other materials havingheat transfer characteristics and dimensional stability satisfactory formolding a matrix bit body, casting a steel bit body or forming variouscomponents associated with well completion tools and well drillingtools. Graphite powders, boron nitride powders and other matrix materialpowders which are stable in temperature ranges associated with formingmatrix bit bodies may be satisfactory used. Such powders may have betterthermal conductivity and/or better dimensional stability as comparedwith some sand and/or plaster powders used to form metal casting molds.

For some applications two or more layers of sand or other materials withdifferent heat transfer characteristics may be used to form molds inaccordance with teachings of the present disclosure. Silica sands, claysands, quartz sand (Sio₂), zircone sand and barium oxide sand areexamples of such different materials which may be used to form a moldwith optimum heat transfer characteristic at specific locations in anassociated mold cavity.

A 3D printer may inject various types of adhesives into each powderlayer to securely bond or bind the powder with itself and with adjacentpowder layers. Examples of such adhesive materials may include, but arenot limited to, one component, adhesive materials, two componentadhesive materials and/or any other adhesive material satisfactory forinjection through the print head of a 3D printer. Non-flammableadhesives may often be used.

A mold having various features such as shown in FIGS. 5A-5D and 6 may bedifficult and time consuming to form using conventional machiningequipment and techniques associated with fabricating conventional moldsused to form bit heads or other components associated with well drilltools and/or well completion tools. Complex configurations andasymmetrical configurations with relative tight dimensional tolerancesmay be formed by 3D printing equipment using 3D design data since theneed to provide machine tool cutting paths and associated machine toolclearances have been eliminated.

One or more of degassing channels and/or fluid channels such as shown inFIGS. 5A-5D and 6 may not be possible to form on a cost effective,commercial basis using conventional machining equipment and mold formingtechniques. Some features of bit heads formed in mold incorporatingteachings of the present disclosure may include highly spiraled bladesalong with mud channels or drilling fluid channels (sometimes referredto as “junk slots”) with complex curved shapes, and/or arcuateconfigurations. Internal tube ways, degassing channels, fluid channelsand cutter pockets having complex and/or asymmetric configurations maybe efficiently and effectively formed in a mold by using 3D printing and3D design data in accordance with teachings of the present disclosure.

Mold assembly 200 formed in accordance with teachings of the presentdisclosure may be described as having a generally cylindricalconfiguration defined in part by first, open end 201 and second, closedend 202 with mold cavity 252 disposed therebetween. For embodiments suchas shone in FIGS. 5A-5D and 6 mold cavity 252 may generally described asa negative image of a bit head for a fixed cutter drill bit (notexpressly shown). Molds formed in accordance with teachings of thepresent disclosure may have generally uniform outside diameters or mayhave variable outside diameters (not expressly shown).

Using three dimensional (3D) computer aided design (CAD) data or other3D design data in combination with a 3D printer and associatedtechniques in accordance with teachings of the present disclosure mayallow forming a plurality of fluid flow channels 206 disposed onexterior portions of mold assembly 200. A plurality of displacements 208may also be formed on interior portions of mold cavity 252 using a 3Dprinter and 3D design data in accordance with teachings of the presentdisclosure.

The configuration and dimensions associated with each displacement 208may be selected to generally correspond with a respective fluid flowpath formed on exterior portions of a resulting bit head. The use of a3D printer in combination with 3D design data allows forming eachdisplacement 208 with a complex, arcuate configuration correspondinggenerally with a desired complex, arcuate configuration for theassociated fluid flow path disposed on exterior portions of theresulting bit head. For some applications each displacement 208 disposedwithin mold cavity 252 may have a unique, complex configuration anddimensions.

For some applications the location of fluid flow channels 206 disposedon exterior portions of mold assembly 200 may generally correspond withthe location of associated displacements 208 disposed within mold cavity252. Each flow channel 206 may also be formed with a respective complex,arcuate configuration designed to optimize heating and/or cooling ofinfiltration materials disposed within mold cavity 252. For someembodiments fluid flow channels 206 may extend from recessed portion orchamber 212 disposed within end 202 of mold assembly 200.

For some applications one or more openings (not expressly shown) may beformed in container 300 to accommodate communication of heating fluidsand/or cooling fluids with chamber 212. The temperature and/or flow rateof such heating and/or cooling fluids may be varied depending uponinfiltration materials disposed within mold cavity 252 and variouscharacteristics associated with a resulting bit head or other component.

Depending upon the type of materials used to form mold assembly 200and/or heating and cooling cycles associated with forming a bit head orother component within mold cavity 252, outgassing may occur. For suchapplications a plurality of internal tube ways or flow paths 214 may beformed within selected portions of mold assembly 200. Flow paths 214 maycommunicate gasses associated with heating and cooling of mold assembly200 to associated fluid flow channels 206 and/or exterior portions ofmold assembly 200. See FIGS. 5A and 5B. The formation of internal tubeways or flow paths 214 may not be commercially possible usingconventional mold forming techniques.

For some embodiments interior portions of mold cavity 252 may be coatedwith a mold wash to prevent gases produced by heating and/or cooling ofmold 250 from entering into powders or matrix materials disposed withinmold cavity 252. Various commercially available washes may besatisfactorily used. The mold wash may form a diffusion barrier orcreate a skin effect to prevent off gases from materials used to formmold 200 from migrating into matrix materials or powders disposed withinmold cavity 252.

Mold cavity 252 may be formed with a plurality of negative bladeprofiles 210 disposed between respective displacements 208. As a resultof forming mold assembly 200 with a 3D printer in combination with 3Ddesign data in accordance with teachings of the present disclosure, eachnegative blade profile 210 may have a respective complex, accurateconfiguration corresponding with a desired configuration for respectiveblades disposed on exterior portions of the resulting bit head.

A plurality of negative pocket recesses or pocket profiles 216 may beformed within each negative blade profile 210. Negative pocket recesses216 may have complex configurations and/or orientations which may not bepossible to economically form using conventional mold formingtechniques. As a result of using a 3D printer in combination with 3Ddesign data in accordance with teachings of the present disclosure,cutting elements may be disposed on exterior portions of a bit head atlocations and/or orientations which may not be commercially possible toform using conventional mold forming techniques.

For other applications, the wall thickness of a mold may be varied toprovide optimum heat transfer at various locations within the moldduring heating and cooling of the mold and materials disposed therein.The present disclosure allows engineering a mold and associatedcontainer for optimum heat transfer characteristics during both heatingand cooling of materials used to form an associated matrix bit head orother components. As a result, the strength of an associated matrix bitbody may be substantially increased as compared with previous molds andmolding techniques used to form matrix bit bodies or other components.

Molds formed in accordance with teachings of the present disclosure maybe disposed in a container formed from graphite based materials, boronbase materials and/or any other materials having satisfactory heattransfer characteristics. Container 300 as shown in FIG. 6 may be formedwith a generally cylindrical configuration having interior portionscompatible with slidably disposing mold assembly 200 therein. Interiorportions of container 300 may be designed to receive correspondingexterior portions of mold assembly 200. For example, second end 302 ofcontainer 300 may have an interior configuration which matches acorresponding exterior configuration of end 202 of mold assembly 200.Container 300 may sometimes be referred to as a “housing”, “crucible” or“bucket”.

A typical roller cone drill bit may include a bit body with an upperportion adapted for connection to a drill string. A plurality of supportarms may depend from a lower portion of the bit body. Each arm generallyincludes a spindle which may protrude radially inward and downward withrespect to a rotational axis of an associated bit body.

Conventional roller cone drill bits are typically constructed in threesegments. The segments may be positioned together longitudinally with awelding groove between each segment. The segments may then be weldedwith each other using conventional techniques to form the bit body. Eachsegment may include an associated support arm extending from the bitbody. An enlarged cavity or passageway may be formed in the bit body toreceive drilling fluids from an attached drill string. U.S. Pat. No.4,054,772 entitled “Positioning System for Rock Bit Welding” shows amethod and apparatus for constructing a three cone rotary rock bit fromthree individual segments.

A cone assembly is generally mounted on each spindle and rotatablysupported on bearings (not expressly shown) disposed between the spindleand a cavity formed in the cone assembly. One or more nozzles may bedisposed in the bit body adjacent to the support arms. The nozzles aretypically positioned to direct drilling fluid passing downwardly fromthe drill string through the bit body toward the bottom or end of awellbore being formed by an associated rotary drill bit.

Rotary drill bit 170 (as shown in FIG. 7) may include bit body 172 withsupport arms 174 and respective cone assemblies 176 extending therefrom.Bit body 172 may also include upper portion 178 with American PetroleumInstitute (API) drill pipe threads 180 formed thereon. API threads 180may be used to releasably engage rotary drill bit 170 with a bottomholeassembly or drill string to allow rotation of rotary drill bit 170 inresponse to rotation of the drill string.

Segment 174 a as shown in FIG. 8 may represent one of three segmentsused to form portions of rotary drill bit 170. Each segment 174 a mayinclude upper portion 182 with respective support arm 174 extendingtherefrom. Each upper portion 182 may form approximately one third ofbit body 172 and associated upper portion 178. Segments 174 a may bewelded with each other using conventional techniques to form a bit bodyfor a roller cone drill bit. For example, notch 184 may be formed inexterior portions of each segment 174 a for use in aligning threesegments 174 a with each other in an appropriate welding fixture. Eachnotch 184 may be removed during machining of various surfaces associatedwith exterior portions of rotary drill bit 170.

An enlarged cavity may be formed within bit body 172 extending throughupper portion 178 to receive drilling fluid from a drill string. One ormore fluid flow passageways (not expressly shown) may also be formed inbit body 172 to direct fluid flow from the enlarged cavity to respectivenozzle housings or receptacles 54.

One or more nozzle receptacles 186 may be formed in exterior portions ofbit body 172. See FIGS. 7 and 8. Each receptacle 186 may be sized toreceive associated nozzle 188. Various types of locking mechanisms 190may be used to securely engage each nozzle 188 in respective nozzlereceptacle 186.

The lower portion of each support arm 170 may include spindle 192. SeeFIG. 8. Spindle 192 may also be referred to as “shaft” or “bearing pin.”Cone assemblies 176 may be rotatably mounted on respective spindles 192extending from support arms 170. Each cone assembly 176 may include arespective cone rotational axis (not expressly shown) correspondinggenerally with an angular relationship between each spindle 192 andassociated support arm 170. The cone rotational axis of each coneassembly 176 may be offset relative to bit rotational axis 196 of rotarydrill bit 170.

Each cone assembly 176 may include a respective backface 198 having agenerally circular configuration. A cavity (not expressly shown) may beformed in each cone assembly 176 extending through associated backface198. Each cavity may be sized to receive associated spindle 192. Varioustypes of bearings, bearing surfaces, ball retainers and/or sealassemblies may be disposed between interior portions of each cavity andexterior portions of associated spindle 192.

For some applications a plurality of milled teeth 80 may be formed onexterior portions of each cone assembly 172. Milled teeth 80 may bearranged in respective rows. A gauge row of milled teeth 80 may bedisposed adjacent to backface 198 of each cone assembly 176. The gaugerow may sometimes be referred to as the “first row” of milled teeth 80.Other types of cone assemblies may be satisfactorily used with thepresent disclosure including, but not limited to, cone assemblies havinginserts and compacts (not expressly shown) disposed on exterior surfacesthereof.

For some applications milled teeth 80 may include one or more layers ofhard, abrasive materials (not expressly shown). Such layers may bereferred to as “hard facing.” Examples of hard materials which may besatisfactorily used to form hard facing include various metal alloys andcermets such as metal borides, metal carbides, metal oxides and metalnitrides.

Each support arm 174 may include respective exterior surfaces 84 and aninterior surface (not expressly shown) with spindle 192 attached theretoand extending therefrom. Each support arm 170 may also include leadingedge 86 and trailing edge 88 with exterior surface 84 disposedtherebetween. Exterior portion 84 may sometimes be referred to as a“shirttail.” Extreme end 90 of each support arm 170 opposite from upperportion 178 of bit body 170 may sometimes be referred to as a “shirttailtip.”

Molds forming in accordance with teachings of the present disclosure maybe used to fabricate various components associated with rotary drill bit170, including but not limited to, segments 174 a and/or cones 176. 3Dprinting equipment and 3D design data may also be used to form models ofsegments 174 a and/or support arms 174. Such models may then be used tofabricate forging dies used to fabricate segments 174 a and/or supportarms 174.

Although the present disclosure and its advantages have been describedin detail, it should be understood that various changes, substitutionsand alternations can be made herein without departing from the spiritand scope of the disclosure as defined by the following claims.

1. A method of forming a mold operable to fabricate at least onecomponent of a well drilling tool comprising: (a) using a threedimensional (3D) printer to deposit a plurality of thin layers of powderhaving a configuration and dimensions based on three dimensional (3D)design data associated with the well drilling tool; (b) using the 3Dprinter to apply binder material to each thin layer of powder; andrepeating steps (a) and (b) to produce the mold with a mold cavityhaving a configuration and dimensions based on the 3D design data forthe associated well drilling tool.
 2. The method of claim 1 furthercomprising using 3D computer aided design (CAD) data.
 3. The method ofclaim 1 further comprising using material selected from the groupconsisting of sand, graphite, metal carbides, metal nitrides and metaloxides to form at least a portion of the powder.
 4. The method of claim1 further comprising selecting the binder material from non-flammableadhesives satisfactory for bonding with each layer of the powder withadjacent layers of the powder to form the mold.
 5. The method of claim 4further comprising selecting the binder material from the groupconsisting of one component adhesives and two component adhesives. 6.The method of claim 1 further comprising forming the mold with exteriordimensions, exterior configuration, interior dimensions and interiorconfiguration optimized for heating and cooling materials placed withinthe mold during formation of the at least one component.
 7. The methodof claim 1 further comprising forming a container having a generallyhollow, cylindrical configuration defined in part by an open, first endsized to receive the mold therein and a second, closed end having aninterior configuration compatible with an associated exteriorconfiguration of the mold.
 8. The method of claim 7 further comprisingforming the container with exterior dimensions, exterior configuration,interior dimensions and interior configuration optimized for heating andcooling the mold disposed within the container.
 9. The method of claim 1further comprising forming portions of the mold with at least twodifferent layers of sand selected to provide optimum heating and coolingof materials placed within the mold during formation of the at least onecomponent.
 10. The method of claim 1 further comprising forming the atleast one component for the well drilling tool selected from the groupconsisting of a bit head, a core bit, a reamer, a near bit reamer, anunder reamer and a hole opener, non-retrievable drilling components,aluminum drill bit bodies associated with casing drilling of wellbores,drill string stabilizers, cones for roller cone drill bits, models forforging dyes used to fabricate support arms for roller cone drill bits,arms for fixed reamers, arms for expandable reamers, internal componentsassociated with expandable reamers, sleeves attached to an up hole endof a rotary drill bit, rotary steering tools, logging while drillingtools, measurement while drilling tools, side wall coring tools, fishingspears, washover tools, rotors, stators or housing for downhole drillingmotors, blades and housings for downhole turbines, and other downholetools having complex configurations or asymmetric geometries associatedwith forming a wellbore.
 11. A method of forming a mold operable tofabricate at least one component of a rotary drill bit comprising: (a)using a three dimensional (3D) printer to deposit a plurality of thinlayers of powder having a configuration and dimensions based on threedimensional (3D) design data associated with the rotary drill bit; (b)using the 3D printer to apply binder material to the thin layer ofpowder; and repeating steps (a) and (b) to produce a mold having a moldcavity with a configuration and dimensions based on the 3D design dataassociated with the rotary drill bit.
 12. The method of claim 11 furthercomprising using material selected from the group consisting of sand,graphite, carbide and boron nitride to form a least a portion of thepowder.
 13. The method of claim 11 further comprising selecting thebinder material from adhesives satisfactory for bonding each layer ofthe powder with adjacent layers of the powder to form the mold.
 14. Themethod of claim 11 further comprising forming the mold with exteriordimensions, exterior configuration, interior dimensions and interiorconfiguration optimized for heating and cooling materials placed withinthe mold during formation of the at least one component.
 15. The methodof claim 11 further comprising forming a container having a generallyhollow, cylindrical configuration defined in part by an open, first endsized to receive the mold therein and a second, closed end having aninterior configuration compatible with an associated exteriorconfiguration of the mold.
 16. The method of claim 17 further comprisingforming the container with exterior dimensions, exterior configuration,interior dimensions and interior configuration optimized for heating andcooling the mold disposed within the container.
 17. The method of claim11 further comprising forming portions of the mold with a variable wallthickness selected to provide optimum heating and cooling of matrixmaterials placed within the mold during formation of a matrix bit heatfor the rotary drill bit.
 18. The method of claim 11 further comprisingforming portion of the mold with a variable wall thickness selected toprovide optimum cooling of a molten steel alloy placed within the moldduring formation of a steel bit head for the rotary drill bit.
 19. Themethod of claim 11 further comprising: forming the mold cavity with aplurality of displacements disposed therein and each displacement havinga complex, arcuate configuration corresponding with a desiredconfiguration for a respective fluid flow path disposed on exteriorportions of the bit head; and forming the mold cavity with a pluralityof negative blade profiles with each negative blade profile disposedbetween associated displacements and each negative blade profile havinga complex, arcuate configuration corresponding with a desiredconfiguration for a respective blade disposed on exterior portions ofthe bit head.
 20. The method of claim 19 further comprising forming aplurality of fluid flow channels disposed on exterior portions of themold with each fluid flow channel located generally proximate one of thedisplacements disposed within the mold cavity.
 21. The method of claim20 further comprising forming each fluid flow channel disposed onexterior portions of the mold with a complex, arcuate configuration. 22.A method of forming a bit head for a matrix bit body comprising: (a)forming a first powder from at least a first infiltration material withheat transfer characteristics and dimensional stability characteristicsin temperature ranges associated the matrix bit body; (b) using a threedimensional (3D) printer to deposit a plurality of thin layers of thefirst powder having a configuration and dimensions based on threedimensional (3D) designed data associated with the bit head; (c) usingthe 3D printer to apply a binder the first material to each thin layerof powder; and repeating steps (b) and (c) to produce the bit headhaving a configuration and dimensions based on the 3D design data forthe matrix bit body.
 23. The method of claim 22 further comprisingselecting the binder material from a group consisting of metallic alloysof copper, nickel, zinc, magnesium, lead, tin, cobalt, silver,phosphorous or mixtures of such metallic alloys.
 24. The method of claim22 further comprising selecting the first infiltration material from agroup consisting of tungsten carbide, monotungsten carbide, ditungstencarbide, macro crystalline tungsten carbide, other metal carbides, metalborides, metal oxides, metal nitrides, polycrystalline diamond (PCD) ormixtures of such infiltration materials.
 25. The method of claim 22further comprising: forming a second powder from a second infiltrationmaterial with heat transfer characteristics and dimensional stabilitycharacteristics in temperature ranges associated with the matrix bitbody; and using the 3D printer to form at least a portion of theplurality of thin layers with the second powder.
 26. The method of claim25 further comprising selecting the second infiltration material from agroup consisting of tungsten carbide, monotungsten carbide, ditungstencarbide, macro crystalline tungsten carbide, other metal carbides, metalborides, metal oxides, metal nitrides, polycrystalline diamond (PCD) ormixtures of such infiltration materials.
 27. A method of forming a moldoperable to fabricate at least one component of a steel bit body for afixed cutter drill bit comprising: (a) using a three dimensional (3D)printer to deposit a plurality of thin layers of powder having aconfiguration and dimensions based on three dimensional (3D) design dataassociated with the at least one component of the steel bit body; (b)using the 3D printer to apply binder material to each thin layer ofpowder; and repeating steps (a) and (b) to produce the mold with a moldcavity having a configuration and dimensions based on the 3D design datafor the associated at least one component.
 28. The method of claim 27further comprising: placing the mold in a container operable to controlcooling of the mold; pouring a molten steel alloy into the mold; andsolidifying the molten steel alloy to form the at least one component.29. The method of claim 28 further comprising forming the mold withexterior dimensions, exterior configuration, interior dimensions andinterior configuration optimized for cooling the molten steel alloyduring solidification of the at least one component.
 30. The method ofclaim 27 further comprising using the 3D printer to deposit theplurality of thin layers of powder to form a mold cavity having aconfiguration and dimensions corresponding with a bit head for the steelbit body.
 31. The method of claim 27 further comprising using the 3Dprinter to deposit the plurality of thin layers of powder to form a moldcavity having a configuration and dimensions operable to form a bit headand a metal shanks as integral components of the steel bit body.
 32. Amethod of forming a mold operable to fabricate at least one component ofa well completion tool comprising: (a) using a three dimensional (3D)printer to deposit a plurality of thin layers of powder having aconfiguration and dimensions based on three dimensional (3D) design dataassociated with the well completion tool; (b) using the 3D printer toapply binder material to the thin layer of powder; and repeating steps(a) and (b) to produce a mold having a mold cavity with a configurationand dimensions based on the 3D design data for the associated wellcompletion tool.
 33. The method of claim 32 further comprising usingmaterial selected from the group consisting of sand, graphite, carbideand boron nitride to form at least a portion of the powder.
 34. Themethod of claim 32 further comprising selecting the binder material fromadhesives satisfactory for bonding each layer of the powder withadjacent layers of the powder to form the mold.
 35. The method of claim34 further comprising selecting the binder material from the groupconsisting of one component adhesives and two component adhesives. 36.The method of claim 32 further comprising forming the mold with exteriordimensions, exterior configuration, interior dimensions and interiorconfiguration optimized for heating and cooling materials placed withinthe mold during formation of the at least one component.
 37. The methodof claim 32 further comprising forming a container having a generallyhollow, cylindrical configuration defined in part by an open, first endsized to receive the mold therein and a second, closed end having aninterior configuration compatible with an associated exteriorconfiguration of the mold.
 38. The method of claim 37 further comprisingforming the container with exterior dimensions, exterior configuration,interior dimensions and interior configuration optimized for heating andcooling the mold disposed within the container.
 39. The method of claim32 further comprising forming portions of the mold with a variable wallthickness selected to provide optimum heating and cooling of materialsplaced within the mold during formation of the at least one component.40. The method of claim 32 further comprising forming the at least onecomponent for a well completion tool selected from the group consistingof production packer components, float equipment, casing shoes, casingshoes with cutting structures, well screen bodies and connectors, gaslift mandrels, downhole tractors for pulling coiled tubing, tool joints,wired (electrical and/or fiber optic) tool joints, drill in wellscreens, rotors, stator or housings for downhole motors, blades orhousings for downhole turbines, latches for downhole tools, downholewireline service tools and other downhole tools have complexconfigurations or asymmetric geometries.
 41. A well drilling toolcomprising at least one component formed using the method of claim 1.42. A rotary drill bit comprising at least one component formed usingthe method of claim
 11. 43. A matrix bit body for a rotary drill bitformed using the method of claim
 21. 44. A well completion toolcomprising at least one component formed using the method of claim 31.45. A mold operable to fabricate a bit head for a bit body comprising: amold cavity extending between a first open end of the mold to a secondclosed end of the mold; a plurality of displacements disposed within themold cavity; each displacement having a complex, arcuate configurationcorresponding with a desired configuration for a respective fluid flowpath disposed on exterior portions of the bit head; a plurality ofnegative blade profiles disposed within the mold cavity betweenassociated displacements; each negative blade profile having a complex,arcuate configuration corresponding with a desired configuration for arespective blade disposed on exterior portions of the bit head; aplurality of fluid flow channels disposed on exterior portions of themold with each fluid flow channel located generally proximate one of thedisplacements disposed within the mold cavity; and each fluid flowchannel disposed on exterior portions of the mold having an arcuateconfiguration.